Sea Waypoint Coordinates - What is the Third Number For?

[GSmith63]

So I want to add waypoints to a campaign, and I see the following as an example:

WaypointPosition=155.2,355.2,60

I know that the first two numbers are the x,y coordinates on the map, but what is the third number for?

[AllQuiet]

So I want to add waypoints to a campaign, and I see the following as an example:

WaypointPosition=155.2,355.2,60

I know that the first two numbers are the x,y coordinates on the map, but what is the third number for?

My guess would be the depth that you start out